Manufacture of hydrogen by the partial liquefaction of gaseous mixtures



Aprii 6 1926. I -1,579,348

G. CLAUDE MANUFACTURE OF' HYDROGEN BY THE PARTIAL LIQUEFACTION OF GASEOUS MIXTURES Filed Jan. 7, 1922 lul I N V EN TOR.

A, ATTORNEYS' raieaiea Api; e, ieee.

GEORGES CLAUDE, E E'AEIs, EEANGE, vAssia LAzoTErNc., A coEroRA'rioN 0E DELAWARE.

MANUEACTUEE 50E HYDEOGEN.

BY'. THEv 'PARTIAL "EIQU'EEACTION 0E. GAsEoUs i' iviIXTUEEs.

application filled lJanuary '7, v1922. Serial No.- 527,542.

To all l1.0710111, z' 1f may con ccm Be it known that I, G'Eonoijis Ummm, va :itizen of the Republic of Fi'aiice, residing at' Paris, in the Republic of.-,France, have` iii-' 5 vented certain new'and .useful Improvements in the Manufacture of` Hydrogen by the Partial 'Liquet'action of Gaseous Mixtures; and I do hereby declare the following to bea full,.clear, and exact description of the in- 0 vention, suchv as will .enable others skilled in scribed with reference particularlyto the extraction of. hydrogen. from a mixture of two gases-of'very different volatility, such for example as hydrogen and carbon-monoxide in water-gas. The" present invention deals with the more complex case'involved in the V.treatment/of 'ordinary coal-gas, coke-oven or othersimilar gases, after the conversion of such mixture of gases a preliminary puri-v fying treatment into La mixture consisting oxide Aand;inethane.' The process according to' the present invention is foundedv essentially on the' discovery that the three last mentioned y gases oftliis mixture, i. e., meth- "when inthe liquid state. VVl'ien-proper advantage be'taken of this fact the serious dif-` `icultie's whichl 'the 'freezing of the methane would cause canbe overcome. The process avoids also 'the 'difficulties occasioned by freezing of the carbon-monoxide in case it is desired to-obtain hydrogen wholly free from this gas, as is. particularly important in the synthesis of ammonia. Y

According to this invention, the process for the-manufacture of hydrogen 'l depends upon the partial liquefaction' of mixtures `of gases of which the main constituents are hydrogen, nitrogen, carbon-monoxide` and methane, such as the mixtures of gases co1n.y

pi'ising the 'aforesaid constituents obtained from coke-oven or like gases after sub3ecting them to `a preliminary purification treatsimply Aof hydrogen, nitrogen, carbon-'mon-v ane, carbon-monoxide and nitrogen, areyto a large extent, miscible with oneanother.

ment'. It consistsin subjecting the vgaseous mixture to be treated, under the desired conditions of compression and-low temperature,

to temperatures whichdeerease progressively from the temperature at which methane boils to a temperature about that at which Non, BY MESNE AssieiiarEizrrs, 'roJ nitrogen freezes under atmospheric pressure,

the conditions of operation of the process being such that the liquid produced flows back in the reverse direction to the flow of the gaseous mixture' treated. whereby the said liquid encounters higher and higher temperatures 'during its backward travel.

For the purpose of the present invention, therefore, the case may be considered of an ascending stream of the 'mixture of gases,-

previously cooled to substantially its dew,

point by circulation in counter-current with the separated gases, and sub]ected during its ascent either in the tubesof a tubular systeni or through the plates of a rectification column to -a temperature4 which decreases regularly from that of the boiling point of pure liquid methane to substantially that of solidification of the most refractory of the three gases above mentioned, namely-the nitrogen. Under these conditions themethane,

the carbon-monoxide and the nitrogenwill condense successively into'.v liquid mixtures flowing in a revcrse'direction vto that of the ascending-stream of 'gascs'and containing successively less and. less methane and-more and more carbon-monoxide, and'nally nitrogen.- The successive liquid 'mixtures are, tlierefore.- more geal.v

and moregdiflicult to con-l succeeding one and will be thus prevented.v I

from reaching a zone where it might freeze-` and stop the working oftheapparatus.' Finally there will remain gaseous hydrogen.

contaminated only iby the very small quantity of nitrogen' which is capable of existing in a gaseous state'at. sucha low temperature.

Since there is a very-great difference between ;the extremev boiling. and freezing -points of-.these liquids, (-210.5o C. 'and 195.50 C. for nitrogen and --184o C. and i649 C. for methane), the best results are obtained 'by collecting and utilizing separately in two or three fractions the liquids .successively formed duringthe vupward passage :of the gases. instead of collecting the 90 A Underthe conditions mentioned, each of.A the gases will be Washed and rectified by the` liquid which flows back in a single portion. Provision is accordingly made for the collection and utilization of several fractions.

Two different considerations, both arising from the fact that a mixture of gases has to be dealt with, the liquids corresponding to which present great differences of volatility, lead to the necessity for dividing the tubular liquetaction system into two or more systems separated by one or two collectors. Thus if, on the one hand, there were only a single tubular system, the liquid nitrogen, iowing back from the higher parts and reaching that part of the apparatus containing boiling methane, where the temperature is, comparatively speaking, very high, would revaporize energetically, and this would obstruct the proper internal working of the apparatus. On the other hand, the single liquid collected under these conditions, (the miscible mixture of nitrogen, carbon-monoxide and methane), would have a temperature much higher than -1950 G., which temperature the liquid nitrogen alone permits of being obtained, and consequently it would be impossible to obtain along the exterior ot the tubular system of the fractionating column the gradation of temperature hereinbct'ore referred to.

By carrying out the process so as to avoid these drawbacks in the manner stated above, there will inally remain gaseous hydrogen, and this hydrogen, which is still in the compressed condition, will furnish, by expanding it with the production of external work,

the cold necessary for carrying out the process. As is known, however, in order to ensure by this expansion the production ot the greatest amount of cold possible, it is necessary to reheat the compressed hydrogen prior to its expansion to the greatest possible extent and this reheating may be eected according to known methods. In the case of the 'present invention, the reheating of the compressed hydrogen may also be effected by causing it to circulate in a liqueier fed by a portion of the compressed cold gas which is delivered to the separating apparatus. In this method of circulation, the hydrogen, because of its cold condition, effects the partial liquefaction of this part of the gas treated, and, consequently, its own temperature is raised. The liquid formed by this liqueaction is sent to the main separating apparatus where the gaseous mixture is treated. The compressed hydrogen is expanded only after this reheating and the expanded hydrogen, which is then very cold, passes on to the separating apparatus in order to produce there, by its very low temperature, the final separation of the gases treated.

In order that the invention may be clearly understood and readily carried into effect, it will now be described more fully with reference to the accompanying drawing which shows diagraminatically, by way ot' example, an apparatus suitable for carrying out the present process. In the drawing the well known exchangers of temperatures in which the compressed gaseous mixture to he treated is cooled by the cold gases issuing from the separating apparatus are not shown.

The cold compressed mixture, after a pre,

vious purilication as mentioned above, and,

consisting, therefore, of hydrogen, nitrogen` carbon-monoxide and methane, is admitted through the pipe A, and the greater part passingl through the regulating valve B enters the separating apparatus proper. This apparatus comprises a column C containing, for example, two nests of tubes D, D1 placed one above the other and provided with collectors E, lill.

The gases entering through the valve l lil-st ascend through the tubes of the nest D. and then, after passing through the second collector El, ascend through the tubes ot' the nest D1. During their ascent the gases, as will be hereinafter explained, are subjected to lower and lower temperatures and tinally at the top ot the tubes D1 they attain a temperature approximating that at which nitrogen saturated with hydrogen freezes. Under these conditions, the liquefaction ol' the methane, the carbon-monoxide and the nitrogen is successively effected in the manner explained above, and the liquids flow back towards the bottoni of the apparatus in proportion to the respective amounts produced and are received in the collectors lil and E1. i In Il liquid methane together with a little carbon-nionoxide is collected. By means of the pipe F, which is provided with a pressure-reducing valve I4", this liquid is delivered into the column C in which the pressure is about atmospheric, at a point about the middle of the column, and it descends over the successive plates G, Gr, G, etc., and evaporates, owing to the internal liqueiaction, losing at first the carbon-monoxide which it contains and thus producing, around the nestiof tubes D, a temperature gradient. In H at the bottom of the column nearly pure methane vaporizes and can be collected.

In El a mixture consisting essentially of carbon-monoxide and nitrogen is collected; this liquid, which is much colder than the preceding one, is delivered by the pipe I which is provided with a pressure-reducing valve I', over the upper plates J, J. J" etc., of the column C. It descends from plate to plate, losing at first mostly nitrogen, then carbon-monoxide and producing around 'the nest of tubes D1 a temperature gradient. On the plates G it meets the liquid coming from the collector E.

' to the surrounding temperature and thereafter utilized. If desired, the methane may also be delivered from the pipe K into a separate compartment of the exchanger in order to collect it separately.

Beyond the upper evaporation compartment of the column C containing the plates J, the nest of tubes-I)l extends into another compartment M of this column, in which the gases are subjected, still under their origlnal pressure, to the action of a temperature ontained as will be hereinafter described and which is still lower than that of nitrogen boiling under atmospheric pressure, so as to complete the elimination of the carbonmonoxide bythe washing to which it is subjected by the last portions of nitrogen. ll'ith this object iii-view, the residual gases -consisting of practically pure hydrogen arriving at. the top of the tubes D1, may be sent to 'expand (with the production of ex@ terna'l work) as completely and eflicaciously as possible, for example, in compound engine or expander N, if-necessary without any intermediate heating. The residual gases are thus reduced to a very low temperature and are sent into the compartment M to circulate around the tubes of the nest D1. However, as has-been mentioned above, this expansion is only entirely satisfactory, if not as regards the final temperature, at least as regardsthe quantity of cold produced, if the gases to be expanded are first subjected to a suitable reheating. For this purpose, for example, they are, in accordance with this invention, first passed through the pipe P around the tubes of the liqueiier Q into which a lportion of the gases to be treated aredelivered through the pipe R. The reheating is carried to the point which insures the productionv of the greatest amount of refrigeration while maintaining at the same time the low temperature required for the purification of the gas, through the upper portions of the tubes of the bundle D. The temperature may Abe the same or higher or lower than the temperature attained when there is no` re heating. The quantity of refrigeration is greater, however, when the gas is re-heated. During the operations so far described the valve S isclosed. The liquid formedin this liqueie'r Q is discharged, together with the non-liquefied hydrogen, through the pipe T provided with a valve T into the'collector lll. In order, however, to ensure that this circulation is suiiicient, it is necessary, by means of a suitable regulation of the valve B, to cause a suitable quantity of the gas to be treated to follow the course through R, Q, T, instead of followingthe course through B. l l

In order to increase the efficiency of the expansion in respect to the amount of cooling v obtained, not only the hydrogen but also the nitrogen and the carbon-monoxide may be caused, on leaving the column, to pass through suitable liqueiiers which are also fed by a portion of the gas to be treated. It has been mentioned that under the conditions realized with the present invention an excellent elimination of the carbon-n'lonoxide is effected by reason of the final washing of the ascending gases by a sui'licient 80 quantityof liquid nitrogen saturated with hydrogen, the temperature of freezing of which liquid is considerably lower than that of carbon-monoxide. lt is possible to benefit by these advantages in the least favorable case, namely that ofwater-gas, which generally contains' only a very small proportion of nitrogen, by treating the water-gas in an apparatus such as that described above, after having added toit a suitableproportion of nitrogen or gares of combustion. lf the proportion ofhydrogen should then become insufficient to furnish by its expansion the desired temperature or quantity of cold necessary, it would sutlice to add also to the gas treated a suitable proportion of the hydrogen produced in the operation of the process, which would amount to making the same quantity of hydrogen circulate indefinitely in the cycle.

It is to be understood that while the in- 'vention has been particularly described in out departing from the essential features as hereinbefore set forth.

I claim: Y l. A process for the manufacture of hydrogen by partial liquefaction of mixtures of gases of which the main constituents are l1ydrogen,"nitrogen', carbon-monoxide and methane, such as the mixtures of gases comprising the aforesaid constituents obtained from coke oven or like gases after subjecting them to a preliminary l`purification treat 120 ment, Which process consists in subjecting the compressed and cold gaseous mixture to be treated to temperatures which decrease progressively from the temperature at which methane boils under about atmospheric pressure to a tempera-ture about that at which nitrogen freezes under about atmospheric pressure, a gas containing substantially the whole of the hydrogen being collected and y the liquids progressively formed being pre-- vented from reachingregions where they.

might freeze by flowing back in the reverse direction to the How of the gaseous mixture treated.

2. A process for the manufacture of hydrogen by partial liquefa-ction of mixtures of gases of which the main constitu-ents are hydrogen, nitrogen, carbon monoxide and methane, such as the mixtures of gases comprising the aforesaid constituents obtained from coke oven or like gases after subjecting them to a prelin'iinary purification treatment, which process consists -in subjecting the compressed and cold gaseous mixture to be treated to teml'ieratures which decrease progressively from the temperature at which methane boilsunder about atmospheric pressure to a temperature about that at which nitrogen freezes under about atmospheric pressure, a gas containing substantially the whole of the hydrogen being collected and the liquids progressively formed being prevented from reaching regions where they might freeze by flowing bach in the reverse direction to the flow of the gaseous mixture treated, those liquids being collected in two or more successive portions separately from one another and being employed for obtaining by their vaporizatiou the above mentioned gradation of temperatures.

3. A process for the manufacture ot hydrogen by partial liquefaetion of mixtures of gases of which the main constituents are hydrogen, nitrogen, carbon monoxide and methane, such as the mixtures of gases comprising the aforesaid constituents obtair-ed from coke oven or like gases after subjecting them to a preliminary purification treatment, which process consists in subjecting the compressed and cold gamous mixture to be treated to temperatures which decrease progressively from the temperature at which methane boils under about atmospheric pressure to a temperature about that at which nitrogen freezes under about atmospheric pressure and the liquids progressively formed being prevented from reaching regions where they might freeze by flowing back in the reverse direction to the flow of the gaseous mixture treated, a gas containing sul'istantially the whole of the hydrogen being collected then heated by circulation in indirect contact with a portion ot the compressed gaseous mixture treated whereby said gaseous mixture is cooled and partially liquefied, the partially heated hydrogen being then expanded with production of cxternal work and the cold expanded hydrogen being utilized for the final purification by liquefaction of the gaseous mixture treated.

4'. A process for the manufacture'of liydrogen from water gas which comprises adding to the Water gas a suitable proportion of nitrogen or of gases of combustion and subjecting the compressed and cold gaseous mixture thus obtained to progressively decreasing temperatures, a gas containing substantially the whole of the hydrogen being collected and the liquids progressively formed being prevented from reaching regions where they might freeze by flowing back in the reverse direction te the flow of the gaseous mixture treated.

5. A process for the separation of the constituents of gaseous mixtures such as those containing hydrogen, nitrogen, carbon monoxide and methane in city or coke oven gases, which comprises subjecting the mixture to selective liquefaction in successive stages, separately collecting the products at each stage, and cvaporating the liquid thus collected by utilizing it in the selective liquefaction of further quantities of gaseous mixture, thereby maintaining a decreasing teinperature gradient to which the gaseous mixture is subjected as it passes through the apparatus, and finally subjecting the gaseous mixture to indirect contact with the cold cxpanded unliqueed residue of the operation.

6. A process for the separation of the constituents ot gaseous mixtures such as those containing hydrogen, nitrogen, carbon monoxide and methane in city or coke oven gases, which comprises subjecting the mixture to selective liquefaction in successive stages, separately collecting the product at each stage, evaporating the liquid thus collected by utilizing' it in the selective liquefaction of further quantities of gaseous mixture, thereby maintaining a decreasing temperature gradient to which the gaseous mixture is subjected as it passes through the apparatus, withdrawing the unliquefied gaseous residue of the operation, raising the temperature of this residue by indirect contact with part of the incoming gaseous mixture, expanding with external work the residue thus warmed and utilizing the cold expanded product to effect the final refrigeration of the gaseous mixture.

7. A process for the separation of the constituents of gaseous mixtures such as those containing hydrogen, which comprises subjecting the mixture to selective liquefaction in successive stages, separately collecting the product at each stage, evaporating the liquid thus collected by utilizing itin the selective liquefaction of further quantities of gaseous mixture, thereby maintaining a decreasing temperature gradient to which the gaseous mixture is subjected as it passes through the apparatus, withdrawing the unliquelied gaseous residue of the operation, raising the temperature of this residue by indirect contact with a portion of the incoming gaseous mixture, expanding with external work the residue thus warmed, utilizing the cold expanded product to effect the final refrigeration of the gaseous mixture and the partial liquefaction of a portion of the gaseous residue. y

8. A process for the separation of the `constituents of gaseous mixtures such as those containing hydrogen, which comprises subjecting the mixture to selective liquefaction in successive stages, separately collecting the product at each stage, evaporating'the liquid thus collected by utilizing it in the selective liquefaction of further quantities of gaseous mixture, thereby maintaining a decreasing temperature gradient to which the gaseous mixture is subjected as it passes through thev apparatus, withdrawing the unliqneed gaseous residue of the operation, raising the temperature of this residue by indirect-contact with a portion of the incoming gaseous mixture, expanding with external work the residue'thus warmed, utilizing the cold expanded product to effect the inal refrigeration of the gaseous mixture and the partial liquefaction of a portion of the gaseous residue, and utilizing the cold evaporated products for the partial liquefaction of distinct portions of the gaseous mixture.

In testimony whereof I aiix my signature.

GEORGES CLAUDE. 

